PROJECT SUMMARY Approximately 15% of the adult U.S. population is affected by chronic kidney disease (CKD), with more than 700,000 in end-stage renal disease (ESRD). ESRD has devastating health, quality of life, and economic consequences, rendering most afflicted patients unable to work and costing Medicare $33.9 billion in 2015. The ESRD population comprises some of the most vulnerable members of society, with minority and low- resource groups disproportionately affected. Arguably, the most disadvantaged group is the subset of patients that receive a sudden and unexpected ESRD diagnosis with no prior planning or nephrological care, which currently accounts for 36% of the total ESRD population. This population suffers increased morbidity and mortality and has limited access to kidney transplantation. Further, the subset of patients that received no or an unknown length of pre-ESRD nephrological care is more likely to be racial/ethnic minorities (40.5% of African American and 42.7% of Hispanic incident patients as compared to 35.1% of Caucasians), compounding existing racial and ethnic disparities within the ESRD population. To date, there has been no U.S.-based examination of the ESRD diagnosis experiences, coping styles and strategies, and renal replacement therapy (RRT) decision-making preferences of patients experiencing this life changing diagnosis under such uniquely traumatic circumstances. Therefore, we propose a study that will compare the ESRD diagnosis experiences, coping styles and strategies, and RRT decision-making preferences of patients who had sudden, unexpected ESRD diagnosis and who were unknown to nephrology, to patients who had expected ESRD diagnosis as part of ongoing nephrological care (Aim 1). We will also assess nephrologists' current practices and perspectives on the manner and timing of RRT education for patients with sudden, unexpected ESRD diagnosis (Aim 2). This multi-methods study will provide a comprehensive understanding of the diagnosis experiences, coping styles and strategies, and RRT decision-making preferences of patients facing sudden and unexpected ESRD diagnosis. The proposed study will contribute important knowledge about patients who have sudden and unexpected ESRD diagnosis and the results of this research will inform clinical practice and the direct care of thousands of patients experiencing sudden and unexpected ESRD diagnosis. Finally, the collected data will serve as the preliminary work needed to inform the development of a RRT decision support tool. The tool will be validated and tested, using a randomized controlled design, to determine its impact on RRT decisions and steps toward kidney transplantation among patients with sudden, unexpected ESRD.